The present invention relates generally to apparatus and methods for conveying objects or materials from one location to another. More particularly, the present invention relates to methods and apparatus for conveying a load or cargo from a storage container. The present invention is advantageously useful for removing a wide variety of loads from an elevated platform and is especially useful for unloading heavy or awkward loads including particulate matter such as sand, gravel, grain and the like from a pickup truck box, trailer box, or any other container which is not equipped with special unloading apparatus such as a typical hoisting means to tilt the box at an inclined angle.
Many devices have been used to unload truck and trailer boxes including apparatus to lift one end of the box to allow the material to run or flow out, hopper bottom complexes, and continuous and non-continuous conveyor mechanisms.
Typical extendible endless belt conveyor systems are shown in U.S. Pat. Nos. 3,158,253 by Reilly; 3,339,650 by Carr; and 3,513,921 by Refer et al. Such conveyor systems are well suited for many purposes and often can be moved from place to place for use. However, such systems require separate loading of the material onto the conveyor system and ar prohibitively expensive for many applications. The tiltable box arrangement and the hopper type systems are likewise suitable for many unloading functions but also increase the cost of the vehicle and/or supporting container as well as rendering them useless for handling a wide variety of loads.
It has been suggested in the prior art that a roller be bolted to the end of a wagon or the like with a sheet-like belt attached to the roller. A hand crank permits winding of the belt onto the roller for skidding the load towards the roller so as to unload the wagon. However, such devices require permanent attachment relative to the storage container and are not adaptable for easy removal and attachment to a wide variety of vehicles or other storage containers.
Thus, there has been a continuing need for a relatively low-cost device which is adaptable for removing a wide variety of loads from cartons to loose particulate material from a storage area without modification to the storage container. Further, many applications demand that such a device be easily removable from the storage container for use in different locations.